Field of the Invention
The invention relates to an X-ray optics assembly for an X-ray diffractometer, including a multilayer mirror, in particular a Goebel mirror, and a switching system with which beam paths for an X-ray beam are selectable. Such an X-ray optics assembly is known from DE 10 2009 047 672 A1, for example.
Description of the Related Art
X-ray diffraction (XRD) is a powerful method of instrumental analytics with which crystalline materials in particular may be characterized. Various measurement geometries are used, depending on the analytical task. For example, the Bragg-Brentano geometry, in which an X-ray beam, after reflection on the sample, is focused on the detector (or the detector aperture), is frequently used in powder diffraction. In the parallel beam geometry, an X-ray beam is directed in parallel onto the sample, for example for texture measurements. For the various measurement geometries, different X-ray optics elements are required in the beam path.
In practice, the same X-ray diffractometer is frequently used with different measurement geometries in alternation. Accordingly, it is desirable to minimize the modification and adjustment measures necessary for switching the measurement geometry.
DE 10 2009 047 672 A1 discloses an X-ray optics design in which a switch is made between a reflection geometry, with an X-ray mirror in the beam path on the primary beam side, and a transmission geometry with two X-ray mirrors in the beam path on the primary beam side, by means of a displaceable or rotatable aperture system. Modification and adjustment operations are thus minimized, or unnecessary.
An X-ray diffractometer is known from U.S. Pat. No. 6,807,251 B2 for measurements in a focusing geometry without reflection on a multilayer mirror, and in a parallel geometry with reflection on the multilayer mirror, whereby one of the beam paths may be selected using a rotatable slitted disk behind the multilayer mirror. In addition, a divergence slit is provided which may be moved between the beam paths.
The known X-ray diffractometers allow a switch between two beam paths, for example a Bragg-Brentano geometry and a parallel beam geometry. For many analytical tasks this is sufficient; in some cases, however, high-resolution X-ray diffraction information is necessary which is not available using the known switchable X-ray optics.
U.S. Pat. No. 6,359,964 B1 describes a device for X-ray analysis, having a parabolic multilayer mirror for parallelizing X-rays, and a device for monochromatizing the parallelized radiation, in particular using a two-crystal monochromator. The multilayer mirror may be rotated by 180°, as the result of which the X-ray beam is directed either via the multilayer mirror and the monochromator onto the object to be examined, or alternatively, directly from the multilayer mirror onto the object. High-resolution X-ray diffraction measurements are possible using the monochromatized X-ray beam.